The design of torsional strength of reinforced concrete beams is used in many standards of many countries around the world, but the provisions and design methods are still different. According to EC2-04 standard based on torsional strength thin-walled tube model, ACI318-19 standard is based on thin-walled tube model and truss - tie model for before and after cracking. Meanwhile, according to TCVN 5574-2018 based on the point of view of warped section. The objective of this study is to investigate the difference between the standards and the accuracy of calculating the torsional resistance of reinforced concrete beams. The predicted torsional strength based on successive design methods EC2 – 04, ACI 318 -19 and TCVN 5574-2018 is compared with the results of 51 reinforced concrete beams tested for pure torsional force. The angle of inclination of the concrete compressive support bars of the ideal truss and tie model is chosen 45°. Keywords: Torsional strength; pure torsion; concrete compression struts; angle of inclination; reinforced concrete.